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Operating bucket elevator without guards

Hi All

In your experience has it been neccesary to operate bucket elevators without guards installed?

i.e. for bucket inspection, do you inspect buckets through a window or cage without removing guards or is this impractical i.e. due to not having a clear view through a window due to dust, etc. If this is the case, when you find a damaged bucket, do you remove the guard - replace the bucket, then replace the guard and continue inspection? or do you allow the operators to continue inspection and hence operating the machine with the guard off?

If you do operate the elevator with the guard off, what risk controls do you utilise to reduce the risk to the operators in this case? For example, inching drives, which allow operation of the belt at a slower speed thereby minimising risk to the operators, or operation at a slow speed provided by variable speed drive?

I am trying to determine some industry consensus for how bucket inspection is done and the controls that people generally use.

If we allow the operators to run the elevator with the guard removed, i.e. at a slow speed, we need to minimise the risk to the operator in the event that the slow speed is exceeded, i.e. due to control system error. If we were using a DOL inching drive there wouldn't be an issue as the inching drive has a fixed speed. However in our case the potential for a VSD speed increase needs to be mitigated to a Category 1 or Category 2 level (per EN954).

In general since a Category 1 system requires well tried components, the use of the VSD to implement the slow speed does not comply. Hence we need to provide a Category 2 or better mitigation in the event we allow the operators to run the elevator with the guard removed.

So you can see my problem - I would rather not allow the operators to run the machine with the guard removed, but whether or not this could be done depends on how practicable this would be - could they do bucket inspection and replacement without operating the machine without guards? How do you do it or how have you seen it done?

Know-How Design (699) John Gateley used this tag 699 times, Coal (268) John Gateley used this tag 268 times, Bulk (217) John Gateley used this tag 217 times

Ifs and Ifs.

There is no need to remove the guard to see the bucket condition.
If the design is correct there will be an observation door which covers a substantial steel grid. This is an age old method to see what is going on with any machine....or should be.
If there is too much dust buy a torch if there is no working lamp within the casing.
If there is that much dust then you won't see sod all even if the guard is removed....or what?
Incidentally the guard must be interlocked with the drive so your idea of running without guards should not be mentioned to anybody again. There are several guard manufacturers who can advise you further before Health and Safety get involved.

Know-How Design (699) John Gateley used this tag 699 times, Coal (268) John Gateley used this tag 268 times, Bulk (217) John Gateley used this tag 217 times

Back to the 1950's....

Such an elevator is a process machine. Most factory regulations demand that a machine must be isolated before access. Therefore if you remove the guard for any reason the machine must stop. No ifs, no buts. If somebody's limb gets detached by an open and moving machine which was considered guard worthy then the remover is liable.
Don't ever think about it. What can happen will happen. I visit plants daily in UK & Europe. Every machine with repetitive shearing operations has signs indicating the severity, pun intended, of the rules. Just because an operator or, in your case, a supplier tells you "Yes but." there are no buts....only one single WHEN.